NPR's Louisa Lim reported from Beijing that the smog "has affected more than 30 cities in China, leading even the official mouthpiece, the People's Daily, to ask plaintively: 'How can we get out of this suffocating siege of pollution?' " As Louisa added:

"China is choking on its own breakneck development, with thousands of new cars taking to the road every day. This year, the pollution has been exacerbated by weather patterns, combined with an unusually cold spell."

" 'In the winter, we have to burn more coal to get heating,' says Zhou Rong of Greenpeace. She says around 50 percent of Beijing's air pollution is historically due to coal-fired power stations. 'Another reason is the weather pattern makes the whole atmosphere very, very stable, and so all the air pollution accumulates down to the ground, so we are getting higher and higher air pollution.' "

Photographers have captured striking sets of smog- and smog-free photos of the Beijing skyline.

"The brightest areas tend to be clouds or fog, which have a tinge of gray or yellow from the air pollution. Other cloud-free areas have a pall of gray and brown smog that mostly blots out the cities below. In areas where the ground is visible, some of the landscape is covered with lingering snow from storms in recent weeks."

At the time the image was captured, NASA reports, the air quality index in Beijing was 341. Levels above 300 are considered "Hazardous." The embassy is posting real-time updates of the air quality index on its website and also on the BeijingAir Twitter feed.

Copyright 2013 National Public Radio. To see more, visit http://www.npr.org/.